Yeh.
It seems unlikely every manufacturer will fill a spot in every class.
Time will tell how's it all run.
Anyway, here's a shot from Japan's unveiling.
Hmm, that is both clearer in showing that each manufacturer will end up with three drivers in a team and confusing in that it then suggests they will all go into the one 24Hr event. Which as per above, isn't going to work when Team Ferrari can't enter a Gr.1 event and vice versa for other teams. So perhaps that image is simplified to give a general overview and there will in fact be several manufacturer vs manufacturer races between the teams, in the different groups.